US9614463B2 - Piezoelectric device, piezoelectric actuator, hard disk drive, and inkjet printer apparatus - Google Patents

Piezoelectric device, piezoelectric actuator, hard disk drive, and inkjet printer apparatus Download PDF

Info

Publication number
US9614463B2
US9614463B2 US14/176,741 US201414176741A US9614463B2 US 9614463 B2 US9614463 B2 US 9614463B2 US 201414176741 A US201414176741 A US 201414176741A US 9614463 B2 US9614463 B2 US 9614463B2
Authority
US
United States
Prior art keywords
piezoelectric
electric field
drive
piezoelectric layer
polarization
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active, expires
Application number
US14/176,741
Other languages
English (en)
Other versions
US20150229238A1 (en
Inventor
Yuiko HIROSE
Yasuhiro Aida
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
TDK Corp
Original Assignee
TDK Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by TDK Corp filed Critical TDK Corp
Priority to US14/176,741 priority Critical patent/US9614463B2/en
Assigned to TDK CORPORATION reassignment TDK CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: AIDA, YASUHIRO, HIROSE, YUIKO
Priority to JP2015004873A priority patent/JP6398734B2/ja
Priority to DE102015101817.9A priority patent/DE102015101817B4/de
Priority to CN201510069985.8A priority patent/CN104835906B/zh
Publication of US20150229238A1 publication Critical patent/US20150229238A1/en
Application granted granted Critical
Publication of US9614463B2 publication Critical patent/US9614463B2/en
Active legal-status Critical Current
Adjusted expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
    • H02N2/00—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction
    • H02N2/0005—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing non-specific motion; Details common to machines covered by H02N2/02 - H02N2/16
    • H02N2/0075—Electrical details, e.g. drive or control circuits or methods
    • H01L41/042—
    • H01L41/1873—
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/802—Circuitry or processes for operating piezoelectric or electrostrictive devices not otherwise provided for, e.g. drive circuits
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/85—Piezoelectric or electrostrictive active materials
    • H10N30/853—Ceramic compositions
    • H10N30/8542—Alkali metal based oxides, e.g. lithium, sodium or potassium niobates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/0207—Driving circuits
    • B06B1/0223—Driving circuits for generating signals continuous in time
    • B06B1/0238—Driving circuits for generating signals continuous in time of a single frequency, e.g. a sine-wave
    • B06B1/0246—Driving circuits for generating signals continuous in time of a single frequency, e.g. a sine-wave with a feedback signal
    • B06B1/0253—Driving circuits for generating signals continuous in time of a single frequency, e.g. a sine-wave with a feedback signal taken directly from the generator circuit
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B2201/00—Indexing scheme associated with B06B1/0207 for details covered by B06B1/0207 but not provided for in any of its subgroups
    • B06B2201/50—Application to a particular transducer type
    • B06B2201/55—Piezoelectric transducer
    • H01L41/0973—
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
    • H02N2/00—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction
    • H02N2/10—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing rotary motion, e.g. rotary motors
    • H02N2/14—Drive circuits; Control arrangements or methods
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/20—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators
    • H10N30/204—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators using bending displacement, e.g. unimorph, bimorph or multimorph cantilever or membrane benders
    • H10N30/2047—Membrane type

Definitions

  • the present invention relates to a piezoelectric device provided with a piezoelectric element including a piezoelectric layer and a drive circuit to control a drive electric field applied to the piezoelectric layer, a piezoelectric actuator by using the piezoelectric device, and a hard disk drive provided with the piezoelectric actuator and an ink-jet printer apparatus.
  • piezoelectric sensors taking advantage of a piezoelectric effect, in which a force applied to a piezoelectric layer is converted to a voltage
  • piezoelectric actuators taking advantage of an inverse piezoelectric effect, in which a piezoelectric layer is deformed when a voltage is applied to the piezoelectric layer, e.g., a hard disk drive head slider and an ink-jet printer head, and a speaker, a buzzer, a resonator, and the like taking advantage of the inverse piezoelectric effect in the same manner.
  • a piezoelectric material showing hysteresis with a small squareness ratio does not have sufficient piezoelectric characteristics depending on the condition of the applied electric field and possibilities of occurrences of polarization degradation and durability degradation due to continuous drive of a piezoelectric element are high.
  • the squareness ratio of a thin film piezoelectric layer is small as compared with that of a bulk piezoelectric material and this tendency is considerable with respect to a lead-free piezoelectric layer.
  • FIG. 1 shows P-E (polarization-electric field) hysteresis, where an electric field is applied to the positive and negative electrode sides until polarization is saturated, in a piezoelectric material showing hysteresis with a relatively small squareness ratio.
  • Electric fields at which polarization becomes 0 are a positive coercive electric field Ec+ and a negative coercive electric field Ec ⁇ .
  • the present invention has been made in consideration of the above-described problems included in the related art and it is an object to obtain a good output from a piezoelectric device by controlling a drive electric field applied to a piezoelectric layer by a drive circuit provided in the piezoelectric device on the basis of dielectric characteristics of the piezoelectric layer employed.
  • a piezoelectric device includes a piezoelectric element including a piezoelectric layer and electrode layers configured to sandwich the piezoelectric layer and a drive circuit to apply an alternating current drive electric field to the above-described piezoelectric layer through the above-described electrode layers, wherein a polarizability ⁇ of the above-described piezoelectric layer in the case where an electric field is applied until polarization is saturated is smaller than 1 ⁇ 10 ⁇ 9 (C/(V ⁇ m)), and the above-described drive circuit has a means to set a minimum value of the above-described drive electric field to become larger than a positive coercive electric field of the above-described piezoelectric layer and a means to set a maximum value of the above-described drive electric field to become smaller than (Pm′(maximum value of polarization) ⁇ Pr′(quasi-remanent polarization))/(1 ⁇ 10 ⁇ 9 ),
  • the minimum value of the drive electric field applied to the piezoelectric layer is set to become larger than the positive coercive electric field and, thereby, the polarization directions of crystal grains constituting the piezoelectric layer are equalized, so that the displacement of the piezoelectric element increases.
  • the maximum value of the drive electric field is set to become smaller than (Pm′ (maximum value of polarization) ⁇ Pr′ (quasi-remanent polarization))/(1 ⁇ 10 ⁇ 9 ) and, thereby, a displacement resulting from rotation of electric dipoles in domains of crystal grains constituting the piezoelectric layer is obtained, so that a larger displacement is obtained.
  • FIG. 2 shows P-E hysteresis of a piezoelectric layer showing hysteresis with a relatively small squareness ratio, where an electric field at which polarization does not reach saturation is applied to the piezoelectric layer.
  • the maximum value of polarization Pm′ refers to the amount of polarization of a piezoelectric layer in the case where the maximum value of a certain applied electric field Ed is applied to the piezoelectric layer
  • 1 ⁇ 10 ⁇ 9 corresponds to the polarizability ⁇ of the piezoelectric layer, and if an electric field is applied to the piezoelectric layer in such a way that (Pm′ ⁇ Pr′)/Ed is larger than 1 ⁇ 10 ⁇ 9 , the piezoelectric layer may be broken because of an electrostrictive effect. Therefore, the maximum value of the drive electric field is set to become smaller than the value at which the applied electric field becomes (Pm′ ⁇ Pr′)/(1 ⁇ 10 ⁇ 9 ).
  • the piezoelectric layer of the piezoelectric device according to the present invention has a coercive electric field on each of a positive electric field side and a negative electric field side
  • the drive circuit of the piezoelectric device has a means to apply a positive electric field in a direction in which an absolute value of the coercive electric field takes on a small value and apply a negative electric field in a direction in which the absolute value of the coercive electric field takes on a large value. Consequently, driving can be performed in an electric field range in which the piezoelectric characteristics of the piezoelectric layer are larger, so that the displacement of the piezoelectric layer can further increase.
  • the drive circuit provided in the piezoelectric device according to the present invention has a means to allow the minimum value of the above-described drive electric field to become more than or equal to 5 times the positive coercive electric field of the above-described piezoelectric layer and allow the maximum value of the above-described drive electric field to become less than or equal to 50 times the positive coercive electric field of the above-described piezoelectric layer. Consequently, a displacement resulting from rotation of electric dipoles in domains of crystal grains constituting the piezoelectric layer is obtained to a larger extent, so that the displacement of the piezoelectric layer can further increase.
  • the piezoelectric layer of the piezoelectric device according to the present invention is made from potassium-sodium niobate.
  • the coercive electric field of potassium-sodium niobate is small as compared with those of the other materials and domains in the crystal grains are small, so that an effect of increasing the displacement by setting the drive electric field is exerted considerably.
  • potassium-sodium niobate may contain Mn, Li, Ta, Ba, Sr, and Zr as additives.
  • a piezoelectric actuator according to the present invention includes the piezoelectric device having the above-described configuration.
  • Specific examples of piezoelectric actuators include a head assembly of hard disk drive and piezoelectric actuator of an ink-jet printer head.
  • a hard disk drive and an ink-jet printer apparatus include the above-described piezoelectric actuator.
  • an output of the piezoelectric actuator can be improved and high performance hard disk drive and ink-jet printer apparatus can be provided.
  • FIG. 1 shows P-E hysteresis in the saturated state of a piezoelectric layer according to the present invention.
  • FIG. 2 shows P-E hysteresis in the unsaturated state of a piezoelectric layer according to the present invention.
  • FIG. 3 is a power-line circuit configuration diagram of a piezoelectric device according to an embodiment of the present invention.
  • FIGS. 4A and 4B are configuration diagrams of a piezoelectric actuator according to the present invention.
  • FIG. 5 is a configuration diagram of a hard disk drive according to the present invention.
  • FIG. 6 is a configuration diagram of an ink-jet printer apparatus according to the present invention.
  • FIG. 3 shows a power-line circuit configuration diagram of a piezoelectric device 1 according to the present embodiment.
  • the piezoelectric device 1 is provided with a piezoelectric element 80 , a drive circuit 20 to control the drive electric field of the piezoelectric element 80 , a current monitoring circuit 30 to monitor a current value flowing into the piezoelectric element 80 , and a switching device 40 , and the piezoelectric element 80 is provided with a first electrode layer 81 , a piezoelectric layer 82 disposed on the first electrode layer 81 , and a second electrode layer 83 disposed on the piezoelectric layer 82 .
  • the piezoelectric element 80 is shown upside down.
  • the first electrode layer 81 is made from, for example, Pt (platinum).
  • the first electrode layer 81 has a thickness of, for example, 0.02 ⁇ m or more and 1.0 ⁇ m or less.
  • the first electrode layer 81 is made from Pt and, thereby, the piezoelectric layer 82 having high orientation property can be formed.
  • a metal material e.g., Pd (palladium), Rh (rhodium), Au (gold), Ru (ruthenium), Ir (iridium), Mo (molybdenum), Ti (titanium), or Ta (tantalum), or an electrically conductive metal oxide, e.g., SrRuO 3 or LaNiO 3 , can be used as the first electrode layer 81 .
  • the first electrode layer 81 can be formed by a sputtering method, a vacuum evaporation method, a printing method, a spin coating method, a sol-gel method, or the like.
  • the piezoelectric layer 82 As for the material used for the piezoelectric layer 82 , a perovskite compound represented by a general formula ABO 3 is mentioned.
  • the piezoelectric layer 82 is made from preferably (K, Na)NbO 3 (potassium-sodium niobate).
  • the piezoelectric layer 82 can be formed by the sputtering method, the vacuum evaporation method, the printing method, the spin coating method, the sol-gel method, or the like.
  • the thickness is specified to be, for example, about 1 ⁇ m or more and 5 ⁇ m or less.
  • the second electrode layer 83 is made from, for example, Pt.
  • the second electrode layer 83 has a thickness of, for example, 0.02 ⁇ m or more and 1.0 ⁇ m or less.
  • a metal material e.g., Pd, Rh, Au, Ru, Ir, Mo, Ti, or Ta, or an electrically conductive metal oxide, e.g., SrRuO 3 or LaNiO 3
  • the second electrode layer 83 can be formed by the sputtering method, the vacuum evaporation method, the printing method, the spin coating method, the sol-gel method, or the like.
  • the piezoelectric element 80 may be coated with a protective film. Consequently, the reliability can be enhanced.
  • an intermediate layer may be provided in any one of or both of between the first electrode layer 81 and the piezoelectric layer 82 and between the piezoelectric layer 82 and the second electrode layer 83 .
  • an electrically conductive oxide is used as for this intermediate layer.
  • SrRuO 3 , SrTiO 3 , LaNiO 3 , CaRuO 3 , BaRuO 3 , (La x Sr 1-x ) CoO 3 , YBa 2 Cu 3 O 7 , La 4 BaCu 5 O 13 , and the like are preferable because the electrical conductivity is high and the heat resistance is provided.
  • a laminate including the above-described piezoelectric element 80 is formed on a predetermined substrate, although the piezoelectric element 80 may not be provided with the substrate.
  • the first electrode layer 81 , the piezoelectric layer 82 , and the second electrode layer 83 are stacked on the substrate and, thereafter, the piezoelectric element 80 is patterned by photolithography. Subsequently, the substrate can be removed by a dry etching method or the like. In the case where the piezoelectric element 80 is provided with the substrate, the substrate may be cut after patterning.
  • the size of the piezoelectric element 80 in the direction perpendicular to the stacking direction is not specifically limited and, for example, about 1.0 mm ⁇ 0.3 mm can be employed.
  • the drive circuit 20 has a function of applying a predetermined electric field to the piezoelectric element 80 .
  • the drive circuit 20 includes a charge pump and is connected to an external power supply 51 , as shown in FIG. 3 , so that a voltage output from the external power supply 51 can be amplified and a predetermined electric field can be output to the piezoelectric element 80 .
  • the piezoelectric device 1 may include the current monitoring circuit 30 in addition to the drive circuit 20 .
  • the current monitoring circuit 30 has a function of applying an electric field to the piezoelectric element 80 and monitoring polarization P at that time and a function of outputting a predetermined electric field value as a signal to the drive circuit 20 .
  • the piezoelectric device 1 may include the switching device 40 .
  • the switching device 40 has a function of electrically switching between connection to the drive circuit 20 and connection to the current monitoring circuit 30 .
  • connection to the current monitoring circuit 30 is performed, and after Eul and Ell signals, which will be described later, obtained from the current monitoring circuit 30 are fed back to the drive circuit 20 , a circuit switching operation is performed.
  • the switching device 40 may be switched after a lapse of a predetermined time and a current monitoring operation may be performed, as described later.
  • the operations of the drive circuit 20 , the current monitoring circuit 30 , and the switching device 40 may be controlled by one integrated circuit collectively. Meanwhile, in the case where a plurality of piezoelectric devices are used in a piezoelectric system, the drive circuit 20 , the current monitoring circuit 30 , and the switching device 40 of the individual piezoelectric devices 1 may be combined into one integrated circuit.
  • the drive circuit 20 provided in the piezoelectric device 1 according to the present invention has a means to set the minimum value Emin of the drive electric field to become larger than a positive coercive electric field Ec+ of the piezoelectric layer 82 and a means to set the maximum value Emax of the drive electric field to become smaller than (Pm′ (maximum value of polarization) ⁇ Pr′ (quasi-remanent polarization))/(1 ⁇ 10 ⁇ 9 ) (C/(V ⁇ m)).
  • the current monitoring circuit 30 and the piezoelectric element 80 are connected by the switching device 40 , and an electric field is applied to the piezoelectric element 80 so as to measure the amount of polarization.
  • the electric field applied at this time is obtained from an external power supply 52 , and the applied electric field to the piezoelectric element 80 is increased from 0 kV/mm to an electric field at which the piezoelectric layer 82 is saturated (maximum value of applied electric field Ed in FIG. 1 ).
  • one back-and-forth operation is performed, where the electric field is returned to 0 kV/mm, is applied up to ⁇ Ed thereafter, and is returned to Ed.
  • a positive coerce electric field Ec+ is obtained by this operation.
  • the lower limit value Ell of the applied electric field is determined from this information, and this electric field is output to the drive circuit 20 .
  • the above-described one back-and-forth operation is performed while the maximum value of applied electric field Ed from the current monitoring circuit 30 to the piezoelectric element 80 is gradually increased in increments of 0.1 kv/mm, and the polarizability ⁇ is determined from (Pm′ (maximum value of polarization) ⁇ Pr′ (quasi-remanent polarization)) and the maximum value of applied electric field Ed on an increase basis (refer to FIG. 2 ). Then, a maximum applied electric field at which the polarizability ⁇ does not exceed 0.1 is determined, this is specified to be the upper limit Eul of the applied electric field, and this electric field is output to the drive circuit 20 .
  • the drive circuit 20 and the piezoelectric element 80 are connected by switching the switching device 40 from the current monitoring circuit 30 to the drive circuit 20 .
  • the drive circuit 20 adjusts Emin and Emax within the range of input Ell to Eul on the basis of the condition and the like set for the drive circuit 20 in accordance with the signals from the piezoelectric system equipped with the piezoelectric device 1 and the characteristics necessary for the piezoelectric system, and fixes the range of the drive electric field to the piezoelectric element 80 .
  • the piezoelectric element 80 is operated within the range of the resulting Emin to Emax by using the external power supply 51 .
  • the direction on the side of the electric field having a small absolute value is specified to be positive
  • the piezoelectric element 80 is operated while the minimum value Emin of the drive electric field is specified to be more than or equal to 5 times the positive coercive electric field Ec+ of the above-described piezoelectric layer 82 and, in addition, the maximum value Emax of the above-described drive electric field is specified to be less than or equal to 50 times the positive coercive electric field Ec+ of the above-described piezoelectric layer 82 . Consequently, the displacement of the piezoelectric element 80 of the piezoelectric device 1 can be further enhanced.
  • the piezoelectric constant of the piezoelectric element 80 constituting the piezoelectric device 1 is measured by the method described below.
  • a predetermined electric field is applied 1 kHz from the power supply 51 to the first electrode layer 81 and the second electrode layer 83 , and the displacement of the piezoelectric element 80 is measured by using a laser displacement meter (produced by Ono Sokki Co., Ltd.). Then, the piezoelectric constant ( ⁇ d31) is obtained by calculation on the basis of the formula described below.
  • FIG. 4A is a configuration diagram of a head assembly mounted on a hard disk drive (hereafter may be referred to as HDD) as an example of piezoelectric actuators including the piezoelectric device according to the present invention.
  • a head assembly 200 includes a base plate 9 , a load beam 11 , a flexure 17 , a piezoelectric device 13 ( 1 ) provided with first and second piezoelectric elements 13 a ( 80 ) serving as driver elements and an element circuit 13 b , and a slider 19 provided with a head element 19 a , as main constituents thereof.
  • the element circuit 13 b is provided with an integrated circuit including a drive circuit, a current monitoring circuit, and a switching device. Meanwhile, a plurality of element circuits to control a plurality of piezoelectric elements may be combined into one integrated circuit.
  • the element circuit 13 b is disposed on a wiring flexible substrate 15 which is part of the flexure 17 , although only a function may be added to a voice coil motor controller on a base of HDD.
  • the load beam 11 includes a base end portion 11 b fixed to the base plate 9 by beam welding or the like, first and second plate spring portions 11 c and 11 d extending from this base end portion 11 b while tapering, an opening portion lie disposed between the first and second plate spring portions 11 c and 11 d , and a beam main portion 11 f following the first and second plate spring portions 11 c and 11 d and extending linearly while tapering.
  • the first and second piezoelectric elements 13 a are disposed on a wiring flexible substrate 15 which is part of the flexure 17 , while keeping a predetermined distance from each other.
  • the slider 19 is fixed to an end portion of the flexure 17 and is rotated in accordance with expansion and contraction of the first and second piezoelectric elements 13 a.
  • the first and second piezoelectric elements 13 a are formed from a first electrode layer, a second electrode layer, and a piezoelectric layer sandwiched between the first and second electrode layers.
  • the piezoelectric actuator according to the present invention can obtain high reliability and a sufficient displacement because this piezoelectric device sets a drive electric field on the basis of examination of the applied electric field at which optimum piezoelectric characteristics provided for the individual piezoelectric elements can be exerted.
  • FIG. 4B is a configuration diagram of a piezoelectric actuator of an ink-jet printer head, as another example of the piezoelectric actuator including the above-described piezoelectric device, and shows an application example of the piezoelectric element 80 in the piezoelectric device 1 .
  • a piezoelectric actuator 300 is formed by stacking an insulating layer 23 , a lower electrode layer 24 , a piezoelectric layer 25 , and an upper electrode layer 26 on a substrate 22 .
  • FIG. 5 is a configuration diagram of a hard disk drive equipped with the head assembly shown in FIG. 4A .
  • a hard disk drive 700 is provided with a hard disk 61 serving as a recording medium and a head stack assembly 62 to record the magnetic information thereto and regenerate in a housing 60 .
  • the hard disk 61 is rotated by a motor, although not shown in the drawing.
  • a plurality of assemblies formed from an actuator arm 64 supported by a voice coil motor 63 in such a way as to rotate freely around a spindle and a head assembly 65 connected to this actuator arm 64 are stacked in the depth direction in the drawing.
  • the head slider 19 is attached to an end portion of the head assembly 65 in such a way as to opposite to the hard disk 61 (refer to FIG. 4A ).
  • the head assembly 65 ( 200 ) a form in which the head element 19 a (refer to FIG. 4A ) is fluctuated in two steps is adopted. Relatively large movements of the head element 19 a are controlled by whole drive of the head assembly 65 and the actuator arm 64 on the basis of the voice coil motor 63 , and fine movements are controlled by drive of the head slider 19 by the end portion of the head assembly 65 .
  • FIG. 6 is a configuration diagram of an ink-jet printer apparatus equipped with the ink-jet printer head shown in FIG. 4B .
  • An ink-jet printer apparatus 800 is configured to primarily include an ink-jet printer head 70 , a main body 71 , a tray 72 , and a head drive mechanism 73 .
  • the piezoelectric actuator 300 is included in the ink-jet printer head 70 .
  • the ink-jet printer apparatus 800 is provided with ink cartridges of four colors of yellow, magenta, cyan, and black in total and is configured to be able to perform full color printing.
  • this ink-jet printer apparatus 800 is provided with an exclusive controller board and the like in the inside, and the ink ejection timing of the ink-jet printer head 70 and scanning of the head drive mechanism 73 are controlled.
  • the main body 71 is provided with the tray 72 on the back and is provided with an automatic sheet feeder (automatic continuous sheet feeding mechanism) 76 in the inside, so as to automatically send recording paper 75 and deliver the recording paper 75 from a front-mounted delivery port 74 .
  • An ink-jet printer apparatus exhibiting high reliability and high safety can be provided by adjusting and applying an electric field, at which optimum piezoelectric characteristics provided for the individual piezoelectric elements can be exerted, with the piezoelectric device used for the piezoelectric actuator of this ink-jet printer head 70 .
  • the first electrode layer 81 serving as a substrate film of the piezoelectric layer 82 was obtained through crystal growth on a 3-inch substrate which is single crystal Si.
  • This first electrode layer 81 was a Pt film and the film thickness was specified to be 0.2 ⁇ m.
  • the forming method was a sputtering method and the film formation was performed while the substrate was heated to 500° C.
  • a sputtering target having a (K 0.5 Na 0.5 )NbO 3 (potassium-sodium niobate) composition was used, and a film of the piezoelectric layer 82 was formed on the first electrode layer 81 .
  • the forming method was a sputtering method and, as with the first electrode layer 81 , the film formation was performed under the condition in which the substrate was specified to be 7500° C.
  • the film thickness was specified to be 2.0 ⁇ m (KNN1).
  • a Pt film was formed as the second electrode layer 83 on the piezoelectric layer 82 .
  • the forming method was the sputtering method as with the first electrode layer 81 , but the substrate temperature was specified to be 200° C.
  • the film thickness was 0.2 ⁇ m.
  • the stacking structure on the substrate was patterned by photolithography, the substrate was removed by dry etching through RIE and, thereby, the piezoelectric element 80 having a movable portion dimension of 0.3 mm ⁇ 1.0 mm was produced.
  • a piezoelectric device 1 including one piezoelectric element 80 and having the circuit configuration as shown in FIG. 3 was formed.
  • ASIC application-specific IC
  • ASIC application-specific IC
  • the maximum value of applied electric field Ed from the current monitoring circuit 30 to the piezoelectric element 80 was gradually increased in increments of 0.1 kv/mm, and the polarizability ⁇ was determined from (Pm′ (maximum value of polarization) ⁇ Pr′ (quasi-remanent polarization)) and the maximum value of applied electric field Ed on an increase basis (refer to FIG. 2 ).
  • the polarizability ⁇ was determined from (Pm′ (maximum value of polarization) ⁇ Pr′ (quasi-remanent polarization)) and the maximum value of applied electric field Ed on an increase basis (refer to FIG. 2 ).
  • 64 kV/mm was obtained as a maximum value of applied electric field Ed at which the polarizability ⁇ did not exceed 0.1 and was maximum, that is, the upper limit Eu 1 of the applied electric field.
  • the lower limit value E 11 and the upper limit value Eul of the applied electric field obtained as described above were input as signals from the current monitoring circuit 30 into the drive circuit 20 , and the switching device 40 was switched from the current monitoring circuit 30 to the drive circuit 20 . Thereafter, in consideration of piezoelectric system constraints and the like, Emin was set at 5 kV/mm and Emax was set at 52 kV/mm. Subsequently, the piezoelectric element 80 was operated by a sinusoidal wave within the range of Emin to Emax.
  • the piezoelectric characteristics of the piezoelectric element 80 were evaluated by using the laser displacement meter (produced by Ono Sokki Co., Ltd.). A sinusoidal wave with a frequency of 1 kHz was applied under the above-described condition of Emin and Emax, the displacement was measured, and the piezoelectric constant ⁇ d31 was determined.
  • the piezoelectric constant ⁇ d31 of the piezoelectric element 80 in Example 1 was 37 ⁇ m/V.
  • a piezoelectric device 1 in Example 2 was formed by using a piezoelectric element 80 having the same characteristics as those in Example 1. At this time, the magnitudes of two coercive electric fields obtained in measurement of the P-E hysteresis by the current monitoring circuit 30 in the piezoelectric device 1 were examined, and contrary to the setting in Example 1, of the two, the coercive electric field having a small absolute value was specified to be Ec+, the application direction of Ec+ was specified to be the positive electric field direction, and the piezoelectric constant was determined in the same manner as that in Example 1.
  • the piezoelectric constant of the same piezoelectric device 1 as that in Example 2 was determined in the same manner as that in Example 1, where setting was performed in such a way that Emin and Emax were limited to more than or equal to 5 times the Ec+ and less than or equal to 50 times the Ec+, respectively, on the basis of the lower limit value Ell and the upper limit value Eul obtained from the current monitoring circuit 30 .
  • a piezoelectric device 1 in Example 4 was formed in the same manner as that in Example 1 except that the film formation temperature of the piezoelectric layer 82 was specified to be 800° C. and the piezoelectric constant was determined in the same manner as that in Example 1.
  • This piezoelectric layer 82 (KNN2) exhibited Ec ⁇ , Ec+, ⁇ , and Eul of 0.67 kv/mm, 1.26 kV/mm, 0.085, and 65 kV/mm, respectively.
  • a piezoelectric device 1 in Example 5 was formed by using the same piezoelectric element 80 as in Example 4.
  • the setting of the current monitoring circuit 30 in the piezoelectric device 1 at this time was specified to be the same as that in Example 2, and the piezoelectric constant was determined in the same manner as that in Example 1.
  • a piezoelectric device 1 in Example 6 was formed by using the same piezoelectric element 80 as in Example 4.
  • the setting of the drive circuit 20 in the piezoelectric device 1 at this time was specified to be the same as that in Example 3, and the piezoelectric constant was determined in the same manner as that in Example 1.
  • a piezoelectric device 1 in Comparative example 2 was formed by using the same piezoelectric element 80 as in Example 4.
  • the setting of the current monitoring circuit 30 in the piezoelectric device 1 at this time was specified to be the same as that in Comparative example 1-3, and the piezoelectric constant was determined in the same manner as that in Example 1.
  • a piezoelectric device 1 in Example 7 was formed in the same manner as that in Example 1 except that the material for the piezoelectric layer 82 was specified to be (Bi 0.5 Na 0.5 )TiO 3 and the piezoelectric constant was determined in the same manner as that in Example 1.
  • This piezoelectric layer 82 (BNT) exhibited Ec ⁇ , Ec+, ⁇ , and Eul of 0.25 kV/mm, 0.53 kV/mm, 0.081, and 60 kV/mm, respectively.
  • a piezoelectric device 1 in Example 8 was formed by using the same piezoelectric element 80 as in Example 7.
  • the setting of the current monitoring circuit 30 in the piezoelectric device 1 at this time was specified to be the same as that in Example 2, and the piezoelectric constant was determined in the same manner as that in Example 1.
  • a piezoelectric device 1 in Example 9 was formed by using the same piezoelectric element 80 as in Example 7.
  • the setting of the drive circuit 20 in the piezoelectric device 1 at this time was specified to be the same as that in Example 3, and the piezoelectric constant was determined in the same manner as that in Example 1.
  • a piezoelectric device 1 in Comparative example 3 was formed by using the same piezoelectric element 80 as in Example 7.
  • the setting of the drive circuit 20 in the piezoelectric device 1 at this time was specified to be the same as that in Comparative example 1-3, and the piezoelectric constant was determined in the same manner as that in Example 1.
  • Example 10 Film formation was performed, where the material for the piezoelectric layer 82 was (K 0.5 Na 0.5 )NbO 3 , the film formation temperature was 700° C., and the film thickness was changed.
  • the film thicknesses of the piezoelectric layers 82 (KNN3) in Examples 10 to 17 at this time were 1.0 ⁇ m, 1.4 ⁇ m, 1.6 ⁇ m, 2.1 ⁇ m, 2.5 ⁇ m, 2.9 ⁇ m, 3.1 ⁇ m, and 3.5 ⁇ m, respectively.
  • Piezoelectric devices 1 in Examples 10 to 17 were formed in the same manner as that in Example 3 except the piezoelectric layer 82 , and the piezoelectric constants were determined in the same manner as that in Example 1.
  • This piezoelectric layer 82 exhibited Ec ⁇ , Ec+, ⁇ , and Eu 1 of about 0.8 kV/mm, 0.4 kV/mm, 0.088, and 100 kV/mm, respectively.
  • Table 1 shows the measurement results of Pm′, Pr′, (Pm′ ⁇ Pr′)/0.1, Ec ⁇ , Ec+, 5Ec+, 50Ec+, and the piezoelectric layer thickness t of the piezoelectric element used in Comparative examples 1-1 to 1-3, 2, and 3 and Examples 1 to 17, Ell and Eul obtained from the current monitoring circuit of the piezoelectric element, Emin and Emax obtained from the drive circuit, and the piezoelectric constant —d31.
  • Examples 10 to 17 there was a tendency of the piezoelectric constant to increase as the film thickness of the piezoelectric layer 82 increased from 1.0 ⁇ m and to decrease when 2.5 ⁇ m was exceeded. The reason for this is estimated that as the film thickness of the piezoelectric layer 82 increases, the crystallinity is improved and the piezoelectric constant increases, although when about 2.5 ⁇ m is exceeded, the crystallinity of the first electrode layer 81 is not inherited and crystals exhibiting different orientation increases.
  • the piezoelectric device by using a circuit to control the drive electric field within an appropriate range can realize a sufficiently large piezoelectric constant.
  • the current monitoring circuit 30 is disposed in addition to the drive circuit 20 .
  • the current monitoring circuit 30 is not indispensable. That is, if a favorable drive electric field range of the piezoelectric element 80 can be determined by a prove measurement or the like, the effect of the present invention is exerted even when the configuration does not include the current monitoring circuit 30 . In that case, the switching device 40 is not necessary, as a matter of course.
  • the piezoelectric element 80 is operated by using the drive circuit 20 and the external power supply 51 , although the piezoelectric element 80 can also be operated by using another power supply included in the piezoelectric device.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Ceramic Engineering (AREA)
  • Particle Formation And Scattering Control In Inkjet Printers (AREA)
  • General Electrical Machinery Utilizing Piezoelectricity, Electrostriction Or Magnetostriction (AREA)
US14/176,741 2014-02-10 2014-02-10 Piezoelectric device, piezoelectric actuator, hard disk drive, and inkjet printer apparatus Active 2034-09-08 US9614463B2 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US14/176,741 US9614463B2 (en) 2014-02-10 2014-02-10 Piezoelectric device, piezoelectric actuator, hard disk drive, and inkjet printer apparatus
JP2015004873A JP6398734B2 (ja) 2014-02-10 2015-01-14 圧電デバイス、圧電アクチュエータ、ハードディスクドライブ、及びインクジェットプリンタ装置
DE102015101817.9A DE102015101817B4 (de) 2014-02-10 2015-02-09 Piezoelektrische vorrichtung, piezoaktor, festplattenlaufwerk und tintenstrahldruckerapparat
CN201510069985.8A CN104835906B (zh) 2014-02-10 2015-02-10 压电装置、压电致动器、硬盘驱动器以及喷墨打印装置

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US14/176,741 US9614463B2 (en) 2014-02-10 2014-02-10 Piezoelectric device, piezoelectric actuator, hard disk drive, and inkjet printer apparatus

Publications (2)

Publication Number Publication Date
US20150229238A1 US20150229238A1 (en) 2015-08-13
US9614463B2 true US9614463B2 (en) 2017-04-04

Family

ID=53676998

Family Applications (1)

Application Number Title Priority Date Filing Date
US14/176,741 Active 2034-09-08 US9614463B2 (en) 2014-02-10 2014-02-10 Piezoelectric device, piezoelectric actuator, hard disk drive, and inkjet printer apparatus

Country Status (4)

Country Link
US (1) US9614463B2 (ja)
JP (1) JP6398734B2 (ja)
CN (1) CN104835906B (ja)
DE (1) DE102015101817B4 (ja)

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6258241B2 (ja) * 2015-02-27 2018-01-10 富士フイルム株式会社 圧電アクチュエータ
WO2017111090A1 (ja) * 2015-12-25 2017-06-29 Tdk株式会社 圧電薄膜、圧電薄膜素子、圧電アクチュエータ、圧電センサ、ヘッドアセンブリ、ヘッドスタックアセンブリ、ハードディスクドライブ、プリンタヘッド、及びインクジェットプリンタ装置
EP3367452A1 (en) * 2017-02-28 2018-08-29 Koninklijke Philips N.V. Electroactive material actuator and drive method
EP3367451A1 (en) 2017-02-23 2018-08-29 Koninklijke Philips N.V. An actuator device incorporating an electroactive polymer actuator and a driving method
JP7013151B2 (ja) * 2017-07-13 2022-01-31 キヤノン株式会社 積層圧電素子、振動子、振動波モータ、光学機器および電子機器
EP3660183B1 (en) * 2018-03-01 2023-07-19 JX Nippon Mining & Metals Corporation Potassium sodium niobate sputtering target and method for producing same
US11456330B2 (en) * 2019-08-07 2022-09-27 Taiwan Semiconductor Manufacturing Company, Ltd. Fatigue-free bipolar loop treatment to reduce imprint effect in piezoelectric device
JP6804615B2 (ja) * 2019-10-21 2020-12-23 住友化学株式会社 圧電膜を有する積層基板、圧電膜を有する素子および圧電膜を有する積層基板の製造方法
JP2022104714A (ja) * 2020-12-29 2022-07-11 セイコーエプソン株式会社 液体吐出装置
DE102022115666A1 (de) 2022-06-23 2023-12-28 Pi Ceramic Gmbh Piezoelektrisches Material mit Perowskitstruktur für hohe Einsatztemperaturen und dessen Herstellungsverfahren

Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2707713A1 (de) 1976-03-01 1977-09-08 Philips Nv Pumpe zum nicht-pulsierenden pumpen von fluessigkeit
US4611260A (en) * 1982-12-15 1986-09-09 Deutsch-Franzosisches-Forschungsinstitut Method and device for polarizing ferroelectric materials
JPH05114760A (ja) 1991-10-22 1993-05-07 Toyota Motor Corp 圧電アクチユエータの駆動方法
EP1001474A1 (en) 1998-11-13 2000-05-17 STMicroelectronics S.r.l. A driver circuit for controlling a piezoelectric actuator in charge mode
DE102006060311A1 (de) 2006-12-20 2008-06-26 Robert Bosch Gmbh Verfahren zum Betrieb eines Einspritzventils
US20080239581A1 (en) * 2006-10-13 2008-10-02 Fujitsu Limited Apparatus for determining contact of head slider and method of determining contact of head slider
US20100182367A1 (en) * 2009-01-16 2010-07-22 Yasunobu Takagi Image forming apparatus, image forming method and computer-readable storage medium
US20100213882A1 (en) * 2009-02-09 2010-08-26 Panasonic Corporation Drive unit
US20110074888A1 (en) * 2009-09-30 2011-03-31 Takamichi Fujii Piezoelectric Actuator, Method of Driving Same, Liquid Ejection Apparatus and Piezoelectric Ultrasonic Osicllator
US20120127136A1 (en) * 2010-08-18 2012-05-24 Kent Displays Incorporated Display device including piezoelectric and liquid crystal layers
US20130200751A1 (en) 2012-02-03 2013-08-08 Agilent Technologies, Inc. Charge correction for piezoelectric actuator
US20130207512A1 (en) * 2011-05-25 2013-08-15 Taiyo Yuden Co., Ltd. Piezoelectric drive element and piezoelectric drive unit
WO2013165384A1 (en) 2012-04-30 2013-11-07 Hewlett-Packard Development Company, L.P. Selecting pulse to drive piezoelectric actuator

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4487536B2 (ja) * 2002-11-15 2010-06-23 パナソニック株式会社 圧電体アクチュエータの駆動方法および圧電体アクチュエータ並びにこれを用いたディスク記録再生装置
JPWO2009072370A1 (ja) * 2007-12-06 2011-04-21 コニカミノルタホールディングス株式会社 液滴吐出ヘッド
JP2010034154A (ja) * 2008-07-25 2010-02-12 Seiko Epson Corp 薄膜圧電素子の製造方法
JP5689651B2 (ja) * 2010-11-09 2015-03-25 エスアイアイ・プリンテック株式会社 液体噴射ヘッド、液体噴射装置及び液体噴射ヘッドの駆動方法
JP2013125914A (ja) * 2011-12-15 2013-06-24 Seiko Epson Corp 液体噴射装置

Patent Citations (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4115036A (en) 1976-03-01 1978-09-19 U.S. Philips Corporation Pump for pumping liquid in a pulse-free flow
DE2707713A1 (de) 1976-03-01 1977-09-08 Philips Nv Pumpe zum nicht-pulsierenden pumpen von fluessigkeit
US4611260A (en) * 1982-12-15 1986-09-09 Deutsch-Franzosisches-Forschungsinstitut Method and device for polarizing ferroelectric materials
JPH05114760A (ja) 1991-10-22 1993-05-07 Toyota Motor Corp 圧電アクチユエータの駆動方法
EP1001474A1 (en) 1998-11-13 2000-05-17 STMicroelectronics S.r.l. A driver circuit for controlling a piezoelectric actuator in charge mode
US20080239581A1 (en) * 2006-10-13 2008-10-02 Fujitsu Limited Apparatus for determining contact of head slider and method of determining contact of head slider
US20100186718A1 (en) 2006-12-20 2010-07-29 Manfred Klein Method for operating an injector
DE102006060311A1 (de) 2006-12-20 2008-06-26 Robert Bosch Gmbh Verfahren zum Betrieb eines Einspritzventils
US20100182367A1 (en) * 2009-01-16 2010-07-22 Yasunobu Takagi Image forming apparatus, image forming method and computer-readable storage medium
US20100213882A1 (en) * 2009-02-09 2010-08-26 Panasonic Corporation Drive unit
US20110074888A1 (en) * 2009-09-30 2011-03-31 Takamichi Fujii Piezoelectric Actuator, Method of Driving Same, Liquid Ejection Apparatus and Piezoelectric Ultrasonic Osicllator
US20120127136A1 (en) * 2010-08-18 2012-05-24 Kent Displays Incorporated Display device including piezoelectric and liquid crystal layers
US20130207512A1 (en) * 2011-05-25 2013-08-15 Taiyo Yuden Co., Ltd. Piezoelectric drive element and piezoelectric drive unit
US20130200751A1 (en) 2012-02-03 2013-08-08 Agilent Technologies, Inc. Charge correction for piezoelectric actuator
DE102013200353A1 (de) 2012-02-03 2013-09-05 Agilent Technologies Inc. Ladungskorrektur für einen piezoelektrischen Aktuator
WO2013165384A1 (en) 2012-04-30 2013-11-07 Hewlett-Packard Development Company, L.P. Selecting pulse to drive piezoelectric actuator

Also Published As

Publication number Publication date
JP2015154076A (ja) 2015-08-24
JP6398734B2 (ja) 2018-10-03
CN104835906B (zh) 2017-04-12
CN104835906A (zh) 2015-08-12
US20150229238A1 (en) 2015-08-13
DE102015101817B4 (de) 2021-09-23
DE102015101817A1 (de) 2015-08-13

Similar Documents

Publication Publication Date Title
US9614463B2 (en) Piezoelectric device, piezoelectric actuator, hard disk drive, and inkjet printer apparatus
JP6299408B2 (ja) 薄膜圧電素子、薄膜圧電アクチュエータ、及び薄膜圧電センサ、並びにハードディスクドライブ、及びインクジェットプリンタ装置
JP4717344B2 (ja) 誘電体薄膜素子、圧電アクチュエータおよび液体吐出ヘッド
US9147827B2 (en) Piezoelectric element, piezoelectric actuator, piezoelectric sensor, hard disk drive, and inkjet printer device
US9837596B2 (en) Piezoelectric device, piezoelectric actuator, piezoelectric sensor, hard disk drive, and inkjet printer apparatus
JP2005175099A5 (ja)
US9022532B1 (en) Piezoelectric element, piezoelectric actuator, piezoelectric sensor, hard disk drive, and ink-jet printer device
JP5321805B2 (ja) アクチュエータ装置の製造方法、液体噴射ヘッドの製造方法、液体噴射ヘッド及び液体噴射装置
CN104395087B (zh) 压电器件、压电致动器、硬盘驱动器、喷墨打印机装置和压电传感器
US10944040B2 (en) Piezoelectric thin film-stacked body, piezoelectric thin film substrate, piezoelectric thin film device, piezoelectric actuator, piezoelectric sensor, head assembly, head stack assembly, hard disk drive, printer head, and ink-jet printer device
CN104603966B (zh) 薄膜压电元件、压电致动器、压电传感器、硬盘驱动器和喷墨打印机装置
JP2011040666A (ja) 圧電アクチュエーターおよびその製造方法、液体噴射ヘッド、液体噴射装置
JP2012089600A (ja) 圧電素子、液滴噴射ヘッドおよび液滴噴射装置ならびに圧電素子の製造方法
WO2017111090A1 (ja) 圧電薄膜、圧電薄膜素子、圧電アクチュエータ、圧電センサ、ヘッドアセンブリ、ヘッドスタックアセンブリ、ハードディスクドライブ、プリンタヘッド、及びインクジェットプリンタ装置
JP2010228266A (ja) 液体噴射ヘッド及び液体噴射装置並びにアクチュエーター
US9277869B2 (en) Thin-film piezoelectric element, thin-film piezoelectric actuator, thin-film piezoelectric sensor, hard disk drive, and inkjet printer apparatus
US20220059753A1 (en) Dielectric thin film, dielectric thin film element, piezoelectric actuator, piezoelectric sensor, head assembly, head stack assembly, hard disk drive, printer head and inkjet printer device
US10790434B2 (en) Piezoelectric thin film-stacked body, piezoelectric thin film substrate, piezoelectric thin film device, piezoelectric actuator, piezoelectric sensor, head assembly, head stack assembly, hard disk drive, printer head, and ink-jet printer device
US20230011057A1 (en) Liquid Ejecting Head And Liquid Ejecting Apparatus
US20230347647A1 (en) Piezoelectric Actuator And Manufacturing Method Thereof, Liquid Droplet Discharge Head, And Ultrasonic Device
JP6237152B2 (ja) 薄膜圧電素子、薄膜圧電アクチュエータ、及び薄膜圧電センサ、並びにハードディスクドライブ、及びインクジェットプリンタ装置
JP2021183379A (ja) 圧電素子、液体吐出ヘッドおよび液体吐出装置
JP2022056335A (ja) 圧電素子、液体吐出ヘッドおよび液体吐出装置

Legal Events

Date Code Title Description
AS Assignment

Owner name: TDK CORPORATION, JAPAN

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:HIROSE, YUIKO;AIDA, YASUHIRO;SIGNING DATES FROM 20140214 TO 20140220;REEL/FRAME:032708/0676

STCF Information on status: patent grant

Free format text: PATENTED CASE

MAFP Maintenance fee payment

Free format text: PAYMENT OF MAINTENANCE FEE, 4TH YEAR, LARGE ENTITY (ORIGINAL EVENT CODE: M1551); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

Year of fee payment: 4